Method and apparatus for the dynamic allocation of signal bandwidth between audio, video and data signals

ABSTRACT

A wireless communication unit for a wireless communication system transmits and receives video, audio and data signals within an RF bandwidth. The RF bandwidth is allocated among the video, audio and data signals to allow the video, audio and data signals to fit within the RF bandwidth. The allocation is performed by buffering the signals, making priority assignments to each of the buffered signals, and transmitting the buffered signals according to the priority assignments. The transmitted signals occupy the RF bandwidth in portions specified by the priority assignments. The priority assignments can be changed during a communication link. The subscriber unit receives a transmission header from another party on the communication link, which may include a request by the other party to change the priority assignments. If such a request is received, the subscriber unit automatically changes the priority assignments in response to the request. The communication unit is applicable to subscriber units and base stations. One such subscriber can be a cellular telephone having full-motion video capability.

BACKGROUND OF THE INVENTION

The invention relates in general to wireless communication systems andin particular to an RF communication system for receiving andtransmitting audio, video and data signals.

Today, wireless data solutions are enabling changes of great scope anddepth in our society. Indeed, the wireless information revolution hasthe potential to democratize the information age like never before.Remotely accessible computers and data systems are becoming more andmore available, putting us all on the verge of a world where anunlimited amount of information will be available anywhere, anytime.

Wireless data capabilities are also improving the productivity andaccessibility of professionals in the field. The ability to send andreceive information over airwaves instead of copper wires is liberatingthe professionals from their offices, giving them immediate access todatabases and streamlining every aspect of their operations. Already,notebook computers equipped with advanced wireless communicationssoftware and radio frequency modems have enabled the formation of"virtual offices," offices that are removed from company headquarters.Now, a market analysts can track the stock market in his car whilesitting in traffic during his commute to work. An engineer, instead ofsitting in his office, can work on a CAD file from the pool side of hishome.

The explosion of wireless data communication has been fueled by advancein semiconductor technology and software. These advances have allowedaudio and data signals to be transmitted over digital networks indigital language, the language of computers.

Digital and mixed signal systems offer many advantages overold-fashioned analog systems. One important advantage is the ability ofdigital systems to transmit and receive more information at higherrates. Whereas analog systems are limited to transmitting audio at arate of 64 Kbps, digital systems can compress audio transmissions andtransmit eight times as much information at the same rate. Moreover,faster processors have allowed digital systems to transmit bits at everincreasing rates. By taking advantage of the ability to transmitinformation more accurately and at higher rates, significant savingshave been realized in both switching capacity and ongoing line costs.

Additional advantages have been realized through the use of multipleaccess techniques such as Time Division Multiple Access ("TDMA") andCode Division Multiple Access ("CDMA"). These techniques allow formultiple users to access a single bandwidth. They also allow for audioand data signals transmitted by a single user to be intermingled. Thesetechniques make better use of scarce airwave space.

A recent development in the wireless information revolution has been thetransmission of video signals over the airwaves. This is now being donein the television industry, as near-perfect images are being transmitteddigitally on the Ku-band from satellites to home-mounted dishes as smallas eighteen inches in diameter. A similar development is occurring inthe cellular telephone industry as efforts are being made to add videocapability to cellular telephones.

Before quality video capability can be added to cellular telephones, aproblem arising from bandwidth limitation must be overcome. Currentcellular telephone systems operate on a frequency of 900 MHZ. Yet evenwith the use of sophisticated compression routines, the bandwidth is notwide enough to transmit the enormous amount of video and audioinformation that is required for quality motion pictures. Bandwidthlimitation may not be a problem for high frequency satellitetransmissions, but it is a problem for the comparatively low frequencyradio transmissions.

Therefore, it is an objective of the present invention to overcome theabove-mentioned bandwidth limitation problem and provide videocommunication capability to a radio frequency communication system.

SUMMARY OF THE INVENTION

The bandwidth limitation problem is overcome by a wireless communicationunit comprising at least one digital transceiver operable to transmitand receive a plurality of data signals over a fixed bandwidth; and acontroller operable to dynamically allocate the fixed bandwidth amongthe plurality of signals. The dynamic allocation is performed by makingpriority assignments to the plurality of signals and transmitting theplurality of signals according to the priority assignments.

The fixed bandwidth can be an RF bandwidth. The plurality of signals caninclude video, audio and data signals.

The communication unit can be a subscriber unit or a base station. Asystem employing the communication units can utilize a multiple accesstechnique such as Time Division Multiple Access or Code DivisionMultiple Access. One embodiment of the communication unit is a videotelephone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a cellular communication system;

FIG. 2 is a block diagram of a subscriber unit according to the presentinvention;

FIG. 3 is a flowchart of steps for the dynamic allocation of an RFbandwidth among video, audio and data signals, the steps being performedby the subscriber unit shown in FIG. 2;

FIG. 4 is a block diagram of a transmitter for the subscriber unit shownin FIG. 2;

FIG. 5 is a block diagram of a receiver for the subscriber unit shown inFIG. 2; and

FIG. 6 is a block diagram of a base station according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a cellular communication system 10 including a plurality ofsubscriber units 12. The subscriber units 12 can include mobile unitssuch as hand held telephones and stationary units such as desktopcomputers. The system 10 also includes a number of base stations 14 thatallow the subscriber units 12 to communicate with each other and withother communication devices in other networks.

The system 10 covers a geographical area that is divided into a grid ofcell sites, with each cell site containing at least one base station 14.Each base station 14 communicates with all subscriber units 12 in itscell site via radio frequency ("RF") signals. One frequency is used fortransmission from the base station 14 to the subscriber units 12 (the"downlink" frequency), and a different frequency is used fortransmission from the subscriber units 12 to the base station 14 (the"uplink" frequency). The system 10 employs "frequency reuse" to allowmore than one base station 14 to operate at the same radio frequency.Each cell site is made large enough so that RF signals crossing a cellsite are attenuated in substantial amount so that they are perceived aslower level noise by base stations in distant cell sites. Frequencyisolation occurs in free space because the RF signals are inherentlyattenuated in proportion to the square of the distance from theradiating source. Isolation is furthered by interference arising fromman-made and natural structures.

One or more frequencies are set aside for setting up a communicationlink or call between the base station 14 and a subscriber unit 12.

The base stations 14 are interlinked with a network controller 16 via adistribution facility such as a dedicated copper wire or fiber opticnetwork, a radio communication link, or a satellite link. The satellitelink provides the highest system capacity. The network controller 16, inturn, provides access to existing wireline telephone networks 17. Eachbase station 14 determines the received signal strength of each call inprogress, and forwards this information to the network controller 16.The network controller 16 uses advanced processing technology to keeptrack of all calls between the subscriber units 12 and base stations 14.The network controller 16 also uses the signal strength information fromeach base station 14 to determine when a call should be "handed off"from the base station in one cell site to the base station in anothercell site. Hand-off allows communication to be maintained with asubscriber unit 12 as the subscriber unit 12 roams from cell site tocell site.

Video, audio and data are transmitted over the airwaves as digitalsignals between the subscriber units 12 and base stations 14. Sources ofvideo, audio and data are not limited to other subscriber units 12 inthe system 10. Since the base stations 14 are linked to telephonenetworks, data can be provided over wired networks by sources such asprivate faxes and corporate computers containing commercial databases.Audio can be provided over wired networks by analog telephones, personalcomputers and even radios. Full-motion video can be provided by directbroadcast satellites and Very Small Aperture Terminals, and by computersover fiber optic and ISDN networks.

Within a cell site, each frequency bandwidth is "shared" by allsubscriber units 12, either through a Time Division Multiple Access("TDMA") technique or a Code Division Multiple Access ("CDMA")technique. The TDMA technique divides up the total bandwidth into apredetermined number of time slots, with each subscriber unit 12 beingallocated a specific time slot. One of the time slots contains animbedded control channel. Each base station 14 continuously transmitstime division multiplexed bit streams to the subscriber units 12 on thedownlink frequency, with each subscriber unit 12 responding bytransmitting bursts on the uplink frequency. Even if a base station 14is not communicating with a subscriber unit 12, a dummy time slottransmission is sent.

The CDMA technique, instead of dividing up the total bandwidth into timeslots, spreads the signal of each subscriber unit 12 across the entirebandwidth. Although each subscriber unit 12 generally occupies theentire bandwidth designated by the base station 14, it utilizes only aportion of the power available to the base station 14. Theinformation-bearing signal is multiplied by a high bandwidth, highfrequency digital spreading signal, which expands the narrow bandwidthinformation-bearing signal into a broad spread signal covering theentire transmission bandwidth. The spreading signal usesquasi-orthogonal bit sequences of period Tc, referred to in the art aschips. The chip sequence causes the cross-correlation function betweensubscriber units 12 to be small, in which event the subscriber units 12are quasi-orthogonal to each other. The chip sequence can be generatedor chosen so that a predetermined or unique chip sequence is assigned toa specific subscriber unit 12 each time the subscriber unit 12 starts acall. This, of course, requires the network controller 16 to maintain acentral log or listing of all user chip sequence assignments.

FIG. 2 shows the subscriber unit 12 for the cellular system 10. Thesubscriber unit 12 includes a transmitter 18, receiver 20, controller22, T/R module 24 and a high efficiency antenna 26. The controller 22defines and implements the protocol for the subscriber unit 12. That is,it defines the convention through which the subscriber unit 12 cancommunicate with the base station 14. The controller 22 decodes theheader of each base station transmission and executes a protocolstructure which controls timing and decision making logic instructions(e.g., timing, message slot selection, T/R control) and other well knownoperations. Prior to a call setup, the subscriber unit 12 monitors airtime, activity, account numbers, and protocol of the base station 14 todetermine whether it can access the system 10. When the subscriber unit12 is ready to make a call, or when a call is transmitted to it, thesubscriber unit 12 establishes a setup channel with a proximate basestation 14. During call setup the base station 14 specifies the uniquetime slots and uplink/downlink frequencies for the subscriber unit 12 totransmit and receive the call.

In addition to those well known operations, the controller 22 allocatesthe RF bandwidth among the audio, video and data signals. Video, audioand data signals to be transmitted are stored in a video buffer 23a, anaudio buffer 23b and a data buffer 23c. Each buffer 23a, 23b and 23c isa queue, a first-in, first-out (FIFO) buffer. The signals are initiallyassigned equal priority (1/3, 1/3, 1/3) of transmission. The priorityassignments are stored in computer memory such as Random Access Memory(RAM) 25. Equal priority assignments means that all three signals occupyequal portions of the RF bandwidth during a transmission by thesubscriber unit 12. Thus, for each transmission, one third of the RFbandwidth is occupied by the video signal, one third of the RF bandwidthis occupied by the audio signal, and the remaining third of thebandwidth is occupied by the data signal. The video, audio and datasignals could be transmitted in sequence, or they could be interleaved.

The priority assignments can be changed. If, for example, the priorityassignments of the video, audio and data signals are changed to 1, 0 and0, the video signal is transmitted over the entire RF bandwidth untilthe video buffer 23a is empty. After the video buffer 23a is emptied,the audio and data signals are transmitted. If the priority assignmentsof the audio and data signals are equal, each will occupy one-half ofthe RF bandwidth during transmission. If the video buffer 23a receivesadditional video, the transmission of the audio and data signals isstopped and the video signal is transmitted until the video buffer 23ais emptied. Then, transmission of the audio and data signals is resumed.

If additional data and audio signals must be transmitted while the videosignal is being transmitted, the audio and data signals are stored inthe audio and video buffers 23b and 23c. If the audio and data buffers23b and 23c become full, the audio and data already stored in thebuffers 23b and 23c are pushed out in order to make room for newsignals. Thus, audio and data is lost at the expense of high qualityvideo.

The priority assignments and, therefore, bandwidth allocation arechanged in response to a request from another party on the communicationlink. If the other party desires a higher quality audio, it sends anappropriate request to the subscriber unit 12. The controller 22responds by transmitting more of the audio signal and buffering more ofthe video and data signals until the fidelity of the transmitted audiomeets the approval of the other party (i.e., when the other party stopsmaking requests for higher audio fidelity).

This requires a protocol that is tailored for dynamic bandwidthallocation of the video, audio and data signals. To implement thisprotocol, four bits in a transmission header are dedicated to therequest. Two of the bits indicate whether the transmission priorityshould be increased, decreased, not changed or reset to presetassignments. The other two bits indicate which signal, whether the videosignal, audio signal or data signal, should be affected by an increaseor decrease. On the transmitting end, the request can be input to thecontroller 22 by means such as a keypad 27. The controller 22 sets thefour bits in the transmission header accordingly.

On the receiving end, the controller 22 constantly checks for requestsfrom the other party by monitoring the transmission headers receivedduring the communication link. When the subscriber unit 12 receives arequest, its controller 22 updates the appropriate priority assignmentsfor the audio and video signals. The signals are buffered and thebuffers 23a, 23b and 23c are emptied in accordance with the priorityassignments. The output of the buffers 23a, 23b and 23c is a serialstream, which is supplied to the transmitter 18.

The transmitter 18 compresses the audio and video signals at rates thatare initially preset. However, the rates can be adjusted by thecontroller 22 to reduce the amount of information being buffered.Following compression, audio, video and data signals are formatted,transported and multiplexed together with the transmission header (whichincludes the four bit request) to form a composite signal. The compositesignal is further processed by the transmitter 18 into either a spreadspectrum signal or a time division multiplexed signal, depending uponwhether CDMA or TDMA is being used by the system 10. The encoded signalis used to modulate a carrier signal. The modulated carrier signal issent to the antenna 26 through the T/R module 24. For subscriber units12 that do not have a video capability, only audio and data signals aremultiplexed with the transmission header to form the composite signal,with compression being performed on the audio signal only.

RF signals received on the antenna 26 are sent to the receiver 20through the T/R module 24. The receiver 20 separates the incoming signalinto four demodulated signals: a compressed video signal, a compressedaudio signal, a data signal and a transmission header. The transmissionheader is sent to the controller 22 and monitored for a request tochange the priority assignments. The compressed video signal, compressedaudio signal and the data signal are unformatted. The compressed signalsare then decompressed using compression rates embedded in the compressedsignals. The decompressed signals, along with the unformatted datasignal, are forwarded to the appropriate interfaces 28 in the subscriberunit 12.

The types of interfaces 28 utilized by the subscriber unit 12 are partlydependent upon whether the unit 12 is stationary or mobile. For a mobilesubscriber unit 12 such as a cellular telephone, the interfaces 28 mustfit within a standard cellular phone case. Audio signals sent from thetransmitter 18 and received by the receiver 20 can be handled bymicrophones, speakers and their associated circuitry in the conventionalmanner. Data signals supplied to the transmitter 18 and received by thereceiver 20 can be transferred in and out of the cellular telephonethrough a serial or parallel port on the case. Video signals received bythe cellular telephone can be synchronized with the audio signals anddisplayed on a small flat panel display mounted to a surface of thecellular telephone's case, or they could be supplied to a CRT through aparallel port on the case. Video signals supplied to the cellulartelephone can be provided on a parallel or serial port on the case. Forexample, an automobile can be equipped with a camera and video capturecard that would supply the video signal to the port. It is even possibleto furnish the cellular telephone with an internal CCD, optical assemblyand video processor for providing video images directly to thetransmitter 18.

Stationary units, especially desktop personal computers, can be equippedwith more elaborate interfaces. Audio signals can be supplied to aresident sound card by a hand held microphone and they can be outputtedfrom the sound card to a speaker system. Data signals can be supplied tothe transmitter 18 directly from computer memory, the computer'smotherboard or from communications ports, and data from the receiver 20can be saved in computer memory, forwarded to a printer or displayed ona CRT. Video signals can be supplied by a hand held camera and aresident video capture card, with the video image from the camera beingquantized by the video capture card in both the spatial domain and theintensity domain. Video signals received by the computer can be saved incomputer memory or displayed directly on the CRT.

A desktop computer having a "PENTIUM" processor or a more powerfulprocessor can be adapted to operate as a subscriber unit 12 with theaddition of only a single card. The transmitter 18, receiver 20, T/Rmodule 24 and interfaces 28 are mounted to the single card, which isinserted into the backplane of the computer. The transmitter 18 andreceiver 20, which perform analog and digital signal processing, are ofmixed signal ASIC designs. It is not necessary to add a controller 22 tothe card; only a Read-Only Memory (ROM) need be mounted. Instructionsfor the controller are stored in the ROM, and the instructions areexecuted by the computer's microprocessor.

FIG. 3 shows the steps 300-348 that are performed by the controller 22for the dynamic allocation of the RF bandwidth among the video, audioand data signals. The controller 22 monitors each transmission headerfor a request to change priority assignments (step 330). If no requestis received (step 332), the controller 22 moves the video, audio anddata from their buffers 23a, 23b and 23c to the transmitter 18 inaccordance with the priority assignments (step 334). Thus, if thepriority assignments are equal, all three signals are equally sent tothe transmitter 18.

If a request is made (step 332), the controller 22 incrementally changesthe priority assignment of the specified signal by an increment of, say,1%, until the request has stopped (step 336). In the meantime, thecontroller 22 is moving the audio, video and data from their buffers23a, 23b and 23c to the transmitter 18 in accordance with the newlyassigned priorities (step 334).

The controller 22 also monitors the buffers 23a, 23b and 23c to detectoverflows (step 338). If there is no danger of an overflow (steps 340and 342), the controller 22 continues to fill the buffers 23a, 23b and23c (step 344). If a particular buffer 23a, 23b or 23c is in danger ofoverflowing (step 340), the controller 22 increases the rate at whichthe transmitter 18 compresses the corresponding signal (step 346). Thisallows the particular buffer 23a, 23b or 23c to be emptied faster. Oncethe danger of overflow has subsided, the compression rate is reset. Ifoverflow occurs, however, the information in the particular buffer 23a,23b or 23c must be overwritten (step 348). Information stored first inthe particular buffer 23a, 23b or 23c is pushed out to make room for newdata.

FIG. 4 shows the functions performed by the transmitter 18. The digitalvideo signal is compressed according to an algorithm that supportsvariable rate compression (block 102). The digital audio signal is alsocompressed according to an algorithm that supports variable ratecompression (block 104). The video and audio signals are normally atrates that are preset, subject to change by the controller 22.

The compressed video signal is broken up into video transport packets(block 106), and the audio signal is broken up into audio transportpackets (block 108). The data signal, although uncompressed, is brokenup into data transport packets (block 110). Each transport packetincludes a header and data portion. In the case of the compressedsignals, the header will indicate whether the compression rates arestored in the first few bytes of the data portion.

Apparatus and methods for compressing the audio and video signals aredisclosed in U.S. patent application Ser. No. 08/580,547, filed Dec. 29,1995 now U.S. Pat. No. 5,784,572 and incorporated herein by reference.The apparatus supports variable rate compression and utilizes multiplecompression algorithms. During a communication link, for example, theapparatus can use an MPEG-1 algorithm for both audio and videocompression. During another communication link, the same apparatus canuse an MPEG-2 algorithm for video compression and Dolby AC3 for audiocompression.

The audio, video and data transport packets are multiplexed togetherwith the transmission header to form a composite signal (block 112). Thetransmission header, which is generated by the controller 22, includesthe four bits that request the other party to change the priorities ofthe video, audio and data signals being transmitted by that party.

The composite signal is then modulated using phase shift keying (PSK)modulation, frequency shift keying (FSK) modulation, or any other typeof modulation suitable for a TDMA or CDMA system (block 114). The PSKmodulation may be any of binary phase shift keying (BPSK) modulation,quadrature phase shift keying (QPSK) modulation, M-ary phase shiftkeying (MPSK) modulation where M is larger than four, or variants ofdifferential phase shift keying (DPSK) modulation.

Following modulation is forward error correction (block 116). Signals tobe transmitted are encoded by coding schemes such as Linear PredictiveCoding (LPC) or Continuously Variable Sloped Delta (CVSD) modulation.Actual data bits forming the input signal are interleaved withadditional bits for ascertaining, or monitoring errors and providing forcorrection.

If the system uses a CDMA technique, the digitally encoded informationsignal is mixed with a spreading chip sequence, which is assigned to thesubscriber unit (block 118). The chip sequence is sent by the subscriberunit to the base station 14 as part of the call setup. It is desirableto spread the communication signal to cover the entire allocatedbandwidth where possible and achieve a high processing gain.

The mixed broad band spread information signal is then mixed with acarrier frequency to produce the communication signals to be transmitted(block 120). The specific frequency used is predetermined by thespectral allocation for the communication system 10. The modulatedsignal is sent to the T/R module 24, which transmits the signal underthe control of the controller 22.

If the system uses a TDMA technique, the digitally encoded informationsignal is used to modulate a carrier frequency only during the allocatedtime slot (blocks 112 and 114). The resulting burst is transmitted bythe T/R module.

FIG. 5 shows the functions performed by the receiver 20. The receiver 20performs low noise amplification on the signal received from the antennaand T/R module and down converts the amplified signal into anintermediate frequency (IF) signal (block 202). Gain control of the IFsignal is performed and the gain-controlled IF signal is mixed to form abaseband signal (block 204). The baseband signal is then locked onto anddemodulated by breaking it into its in-phase (I) and quadrature (Q)components, which are converted into a digital signal (block 206). Thedigital signal is deinterleaved and decoded at a predetermined decodingrate by a convolutional decoder such as a Viterbi algorithm decoder(block 208). The decoded signal is then demultiplexed into atransmission header and video, audio and data transport packets (block210). The transmission header is supplied to the controller 22 and theaudio, data and video signals are sent to an inverse transport processor(block 212). The compressed audio and video signals are thereafterdecompressed using the audio and video compression rates embedded in thedata portion of the transport packet (block 214). The decompressed videoand audio signals are synchronized (if corresponding audio istransmitted) and then forwarded, along with the unformatted data signal,to the appropriate interfaces 28.

FIG. 6 shows the base station 12 for the cellular system 10. Signalsreceived by an antenna 40 are supplied to a receiver module 44 via a T/Rmodule 42. For a CDMA system, the receiver module 44 includes a powersplitter which sends the incoming signal to a plurality of receivers,each of which handles a specific communication link. Thus, each basestation 14 for a CDMA system will employ as many receivers ascommunication links it is expected to establish at a given time. Allreceivers for the CDMA function in substantially the same manner as thereceiver 20 shown in FIG. 5, except that they employ narrower bandfilters and timing loops instead of pilot tracking circuitry. For a TDMAsystem, the receiver module 44 contains a single receiver that functionsin substantially the same manner as the receiver shown in FIG. 5, exceptthat it includes a demultiplexer and associated circuitry for forwardingthe received bursts onto separate communication links.

Digital audio, data and video signals are supplied to a plurality oftransmitters 46, each of which is dedicated to a specific communicationlink. The modulated carrier signals from the various transmitters 46 arecombined by a transmit combiner 48. In the case of the TDMA system, thebursts from the transmitters 46 are combined at their selected timeslots to provide a continuous stream of time-division multiplexedinformation. In the case of the CDMA system, the spread spectrum signalsare combined to provide a composite spread spectrum signal. The combinedtransmit signal from the transmit combiner 48 is then supplied to theantenna 40 through the T/R module 42.

The base station 14 is controlled by a cell site controller 50 in thesame manner that a subscriber unit 12 is controlled by its controller22, except that the cell site controller 50 directs the base station 14to communicate with all of the subscriber units 12 on all of thecommunication links. The cell site controller 50 also determines signalstrength information necessary for a hand-off decision, and passes theinformation to the network controller 16.

The base station 14 also includes an interface 52 for sending the video,audio and data signals in digital form to the network controller 16. Thenetwork controller 16 places the audio, video and data signals on atelephone network, sends the signals to other base stations, places themon a satellite link, etc. If the base station 14 has direct access to anexisting telephone network, the interface 52 would include data-to-audiodecoders for sending analog audio signals over the network andaudio-to-data encoders for receiving the analog audio signals.

Thus disclosed is an RF communication system that overcomes the problemof bandwidth limitation associated with the transmission of audio andhigh quality video signals. The problem is overcome by dynamicallyallocating the bandwidth among the audio and video signals.

Further disclosed is a protocol for the transmission of audio and videosignals. Protocols for current TDMA and CDMA systems are not optimizedfor allocating the RF bandwidth during a communication link.

Still further disclosed is a cellular telephone having qualityfull-motion video capability.

It is understood that various changes and modifications may be madewithout departing from the spirit and scope of the invention. It is alsounderstood that use of the invention is not limited to CDMA and TDMAcommunication systems, but can be applied to any other type of narrowbandwidth communications system. Accordingly, the present invention isnot limited to the precise embodiment described hereinabove.

What is claimed is:
 1. A wireless system for the communication of video,audio and data signals over an RF bandwidth, comprising:a plurality ofsubscriber units operable to allocate the RF bandwidth among the video,audio and data signals by making priority assignments of transmission tothe video, audio and data signals; a plurality of base stations coveringa geographical area divided into a plurality of cell sites, each basestation being operable to establish RF communications links with thesubscriber units in its cell site; and a network controller connected tothe plurality of base stations; wherein each subscriber unit receives aplurality of transmission headers during a communication link, eachtransmission header including a number of bits indicating whether arequest to change the priority assignments between the video, audio anddata signals has been made.
 2. The system of claim 1, wherein the numberof bits indicate whether a priority assignment of one of the signalsshould be increased, decreased or unchanged.
 3. The system of claim 1,wherein the transmission header includes four bits for indicatingwhether a priority assignment of one of the signals should be increased,decreased or unchanged.
 4. The system of claim 1, wherein at least onesubscriber unit comprises:a digital transceiver operable to transmit andreceive a data signal and compressed video and audio signals over the RFbandwidth; and a controller operable to dynamically allocate the RFbandwidth among the video, audio and data signals prior to transmission,the dynamic allocation being made in response to the transmission headerof a received signal.
 5. The system of claim 1, wherein at least onebase station comprises:at least one digital transceiver operable totransmit and receive data signals and compressed video and audio signalsover the RF bandwidth; and a controller operable to dynamically allocatethe RF bandwidth among the video, audio and data signals prior totransmission, the dynamic allocation allowing the video, audio and datasignals to be transmitted within the RF bandwidth.
 6. A mobile videotelephone, comprising:a digital transceiver operable to transmit andreceive a data signal and compressed video and audio signals over an RFbandwidth; a controller operable to dynamically allocate the RFbandwidth among the video, audio and data signals, the dynamicallocation being performed by making priority assignments to each of thevideo, audio and data signals and transmitting the video, audio and datasignals according to the priority assignments; and a display fordisplaying a video signal received by the transceiver; wherein thecontroller performs the steps of:buffering the video, audio and datasignals to be transmitted; making the priority assignments to each ofthe buffered signals; supplying the buffered signals to the transceiversuch that the buffered signals, when transmitted, occupy the fixedbandwidth in portions specified by the priority assignments.
 7. Thevideo telephone of claim 6, wherein the transceiver includes:an antenna;a T/R module coupled to the antenna; a receiver having an input coupledto the T/R module; and a transmitter having an output coupled to the T/Rmodule.
 8. The video telephone of claim 7, wherein the receiverincludes:a demodulator for demodulating an incoming signal from the T/Rmodule; a demultiplexer for separating the demodulated signal into atransmission header and video, audio and data signals, the transmissionheader being supplied to the controller; a first decompressor fordecompressing the video signal according to a rate embedded in the videosignal; and a second decompressor for decompressing the audio signalaccording to a rate embedded in the audio signal.
 9. The video telephoneof claim 7, wherein the transmitter includes:a first compressor forcompressing the video signal to fit within a video bandwidth supplied bythe controller; a second compressor for compressing the audio signal tofit within an audio bandwidth supplied by the controller; a combiner forcombining the compressed video and audio signals; a PSK modulatorresponsive to an output of the combiner; and a carrier frequencymodulator, responsive to an output of the PSK modulator.
 10. The mobilevideo telephone of claim 6, wherein the controller performs theadditional step of changing the rates of compression of select signals,whereby the transceiver increases the compression of the correspondingsignals.
 11. The mobile video telephone of claim 6, wherein thecontroller performs the additional steps of:receiving signals includingtransmission headers from another party when a communication link withthe other party has been established; monitoring the transmissionheaders for requests to change the priority assignments; and changingthe priority assignments in response to the requests, whereby thebandwidth are allocated among the signals in accordance with therequests.
 12. A wireless communication unit, comprising:at least onedigital transceiver operable to transmit and receive a plurality ofsignals comprising at least two from the group consisting of videosignals, audio signals, and data signals; a controller operable todynamically allocated the fixed bandwidth among the plurality ofsignals, the dynamic allocation being performed by making priorityassignments to each of the plurality of signals and transmitting theplurality of signals according to the priority assignments, wherein saidcontroller supplies buffered signals to the transceiver such that thebuffered signals, when transmitted, occupy the fixed bandwidth inportions specified by the priority assignments; and a plurality ofqueues corresponding to the plurality of buffers, the controllerbuffering the plurality of signals in the queues; wherein the controllerperforms the steps of:buffering the signals to be transmitted; makingthe priority assignments to each of the buffered signals; receivingsignals including transmission headers from another party when acommunication link with the other party has been established; monitoringthe transmission headers for requests to change the priorityassignments; and changing the priority assignments in response to therequests, whereby the fixed bandwidth is allocated among the pluralityof signals in accordance with the requests.
 13. The communication unitof claim 12, wherein the priority assignments are changed incrementallyuntil the requests have stopped.
 14. The communication unit of claim 13,wherein each request occupies four bits in the transmission header. 15.A wireless communication unit, comprising:at least one digitaltransceiver operable to transmit and receive a plurality of signals overa fixed bandwidth; and a controller operable to dynamically allocate thefixed bandwidth among the plurality of signals, the dynamic allocationbeing performed by making priority assignments to each of the pluralityof signals and transmitting the plurality of signals according to thepriority assignments wherein the communication unit is a subscriberunit; wherein the transceiver includes:an antenna; a T/R module coupledto the antenna; a receiver having an input coupled to the T/R module;and a transmitter having an output coupled to the T/R module; andwherein the receiver further includes:a demodulator for demodulating anincoming signal from the T/R module; a demultiplexer for separating thedemodulated signal into a transmission header and the plurality ofsignals, the transmission header being supplied to the controller; andat least one decompressor for decompressing select signals of theplurality according to rates embedded in the select signals.
 16. Awireless communication unit, comprising:at least one digital transceiveroperable to transmit and receive a plurality of signals over a fixedbandwidth; and a controller operable to dynamically allocated the fixedbandwidth among the plurality of signals, the dynamic allocation beingperformed by making priority assignments to each of the plurality ofsignals and transmitting the plurality of signals according to thepriority assignments wherein the communication unit is a subscriberunit; wherein the transceiver includes:an antenna; a T/R module coupledto the antenna; a receiver having an input coupled to the T/R module;and a transmitter having an output coupled to the T/R module; andwherein the transmitter further includes:at least one compressor forcompressing select signals of the plurality at compression ratessupplied by the controller; a combiner for combining the plurality ofsignals; a PSK modulator responsive to an output of the combiner; and acarrier frequency modulator, responsive to an output of the PSKmodulator.
 17. The communication unit of claim 16, wherein thetransmitter further includes an encoder between the combiner and PSKmodulator for generating a code division spread spectrum signal from anoutput of the combiner, the spread spectrum signal being supplied to thePSK modulator.
 18. The communication unit of claim 16, wherein thetransmitter further includes an encoder between the combiner and PSKmodulator for generating a time division multiplexed signal from anoutput of the combiner, the time division multiplexed signal beingsupplied to the PSK modulator.
 19. A method of communicating a pluralityof signals within an RF bandwidth, comprising the steps of:makingpriority assignments to each of the plurality of signals; transmittingthe plurality of signals within the RF bandwidth according to thepriority assignments, wherein the transmitted signals occupy the RFbandwidth in portions specified by the priority assignments; bufferingthe signals prior to the step of making the priority assignments,wherein the signals are buffered on a first-in, first-out basis;establishing a communication link with another party; receiving signalsincluding transmission headers from the other party; monitoring thetransmission headers for requests to change the priority assignments;and changing the priority assignments in response to the requests,whereby the RF bandwidth is allocated among the plurality of signals inaccordance with the requests.
 20. The method of claim 19, wherein thepriority assignments are changed incrementally until the requests havestopped.
 21. A method of communicating a plurality of signals within anRF bandwidth, comprising the steps of:making priority assignments toeach of the plurality of signals; transmitting the plurality of signalswithin the RF bandwidth according to the priority assignments, whereinthe transmitted signals occupy the RF bandwidth in portions specified bythe priority assignments; buffering the signals prior to the step ofmaking the priority assignments, wherein the signals are buffered on afirst-in, first-out basis; receiving a transmission; demodulating thetransmission; separating the transmission into video, audio and datasignal; decompressing the video signal according to a rate embedded inthe video signal; and decompressing the audio signal according to a rateembedded in the audio signal.